A number of devices have been used in the art to facilitate the horizontal movement of scenery panels for staged productions of various types. Typically, they have taken forms similar to drapery rods.
Among related devices are a carriage and rail assembly for a curtain described in U.S. Pat. No. 5,542,149 to Yu. Figures 6 and 7 of that patent set forth a prior art device which includes twin horizontal tracks for guiding a carriage suspended on axles connecting pairs of wheels riding in the tracks, with the curtain suspended between the tracks. Various stresses on the carriage during movement of a supported curtain, can cause uneven loading and upward and sideward biasing of the wheels. This subjects the wheels to damage, breaking and difficult movement. To improve on this structure, pairs of displacement-limiting rollers are added to oppose upward and sideward displacement from the tracks. While an apparent improvement on the prior art, this arrangement requires a total of ten wheels per carriage for carrying a single curtain. It would be desirable to reduce the complexity of such a carriage and rail assembly and yet provide the capability to hold and convey a plurality of curtains or scenery panels.
In U.S. Pat. No. 4,073,034, Martens describes a system for supporting and moving panels of a multi-panel door which also includes upper and lower rollers to maintain alignment on a track. Two door panels are shown supported on the same track and move in coordinated fashion, with one moving at twice the speed of the other. There is no provision made for two parallel tracks for independently moving two individual panels or for supporting panels on two sides to provide greater stability against sway transverse to the direction of movement and resulting torsional dislodgment in situations where that might be a problem. In addition, the device described cannot provide good stability against rocking in the direction of movement unless a multiplicity of hangers are provided for each panel. It would be desirable to have a carriage assembly having greater stability and versatility.
In U.S. Pat. No. 4,698,876, Karita shows a variation on the Martens-type of arrangement, but enables a magnetic force to support at least a part of the weight of the door. The improvements described in the patent do not, however, adapt it to the needs addressed by the present invention.
The above and other drapery and panel door hangers are available, but the art of supporting and moving theatrical scenery panels is awaiting the development of an apparatus for supporting such panels and facilitating their horizontal movement quietly, smoothly, with low frictional resistance and in a highly-linear fashion with low rock and sway.